A pharmacophore design approach, based on the coordination chemistry of an intimate molecular hybrid of active metabolites of pro-drugs, known to release active species upon enzymatic oxidative activation, is devised. This is exemplified by combining two anti-mycobacterial drugs: pyrazinamide (first line) and delamanid (third line) whose active metabolites are pyrazinoic acid (PyzCOOH) and likely nitroxyl (HNO (or NO^.)), respectively. Aiming to generate those active species, a hybrid compound was envisaged by coordination of pyrazine-2-hydroxamic acid (PyzCONHOH) with a Na₃[Fe^II(CN)₅] moiety. The corresponding pentacyanoferrate(II) complex Na₄[Fe^II(CN)₅(PyzCONHO⁻)] was synthesized and characterized by several spectroscopic techniques, cyclic voltammetry, and DFT calculations. Chemical oxidation of this complex with H₂O₂ was shown to induce the release of the metabolite PyzCOOH, without the need of the Mycobacterium tuberculosis (Mtb) pyrazinamidase enzyme (PncA). Control experiments show that both H₂O₂- and N-coordinated pyrazine Fe^II species are required, ruling out a direct hydrolysis of the hydroxamic acid or an alternative oxidative route through chelation of a metal center by a hydroxamic group. The release of HNO was observed using EPR spectroscopy in the presence of a spin trapping agent. The devised iron metal complex of pyrazine-2-hydroxamic acid was found inactive against an actively growing/non-resistant Mtb strain; however, it showed a strong dose-dependent and reversible vasodilatory activity with mostly lesser toxic effects than the reference drug sodium nitroprussiate, unveiling thus a potential indication for acute or chronic cardiovascular pathology. This is a priori a further indirect evidence of HNO release from this metal complex, standing as a possible pharmacophore model for an alternative vasodilator drug.

设计了一种药效基团设计方法，该方法基于前药活性代谢物的紧密分子杂化体的配位化学，已知该酶在酶促氧化激活后会释放出活性物质。这可以通过将两种抗分枝杆菌药物：吡嗪酰胺（第一行）和德拉曼尼德（第三行）组合来举例说明，它们的活性代谢产物分别是吡嗪酸（PyzCOOH）和可能的硝酰基（HNO（或NO ^。））。为了产生那些活性物质，设想通过吡嗪-2-异羟肟酸（PyzCONHOH）与Na ₃ [Fe ^II（CN）₅ ]部分的配位来形成杂化化合物。相应的五氰基高铁酸盐（II）络合物Na ₄ [Fe ^II（CN）₅（PyzCONHO ^-）]的合成和表征由几个光谱技术，循环伏安法，和DFT计算。已证明该复合物与H ₂ O _2的化学氧化可诱导代谢物PyzCOOH的释放，而无需结核分枝杆菌（Mtb）吡嗪酰胺酶（PncA）。对照实验表明，H ₂ O ₂和N配位的吡嗪Fe ^II需要一种异种，排除了异羟肟酸的直接水解或通过异羟肟基与金属中心螯合的另一种氧化途径。在自旋俘获剂的存在下，使用EPR光谱法观察到HNO的释放。发现设计的吡嗪-2-异羟肟酸的铁金属配合物对活跃生长的/非抗性的Mtb菌株无效。然而，与参考药物硝普钠相比，它显示出强的剂量依赖性和可逆性血管舒张活性，且毒性作用要小得多，从而揭示了急性或慢性心血管疾病的潜在适应症。这是先验的另一间接证据，表明该金属络合物释放出HNO，可作为替代血管扩张药的可能的药效团模型。